prowler/checks/check_extra778

#!/usr/bin/env bash

# Prowler - the handy cloud security tool (copyright 2019) by Toni de la Fuente
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License. You may obtain a copy
# of the License at http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software distributed
# under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
# CONDITIONS OF ANY KIND, either express or implied. See the License for the
# specific language governing permissions and limitations under the License.

CHECK_ID_extra778="7.78"
CHECK_TITLE_extra778="[extra778] Find VPC security groups with wide-open public IPv4 CIDR ranges (non-RFC1918) (Not Scored) (Not part of CIS benchmark)"
CHECK_SCORED_extra778="NOT_SCORED"
CHECK_TYPE_extra778="EXTRA"
CHECK_ALTERNATE_check778="extra778"

extra778(){
    CIDR_THRESHOLD=24
    RFC1918_REGEX="(^127\.)|(^10\.)|(^172\.1[6-9]\.)|(^172\.2[0-9]\.)|(^172\.3[0-1]\.)|(^192\.168\.)"
    textInfo "Looking for VPC security groups with wide-open (</${CIDR_THRESHOLD}) non-RFC1918 IPv4 address ranges in all regions...  "

    check_cidr() {
        local SECURITY_GROUP=$1
        local DIRECTION=$2
        local DIRECTION_FILTER=""
        local REGION=$3
        
        case ${DIRECTION} in
            "inbound")
                DIRECTION_FILTER="IpPermissions"
                ;;
            "outbound")
                DIRECTION_FILTER="IpPermissionsEgress"
                ;;
        esac

        CIDR_IP_LIST=$(aws ec2 describe-security-groups \
                        --filter "Name=group-id,Values=${SECURITY_GROUP}" \
                        --query "SecurityGroups[*].${DIRECTION_FILTER}[*].IpRanges[*].CidrIp" \
                        --region ${REGION} \
                        --output text | xargs
                        )
        
        for CIDR_IP in ${CIDR_IP_LIST}; do
            if [[ ! ${CIDR_IP} =~ ${RFC1918_REGEX} ]]; then
                CIDR=$(echo ${CIDR_IP} | cut -d"/" -f2 | xargs)

                # Edge case "0.0.0.0/0" for RDP and SSH are checked already by check41 and check42
                if [[ ${CIDR} < ${CIDR_THRESHOLD} && 0 < ${CIDR} ]]; then
                    textFail "${REGION}: ${SECURITY_GROUP} has potential wide-open non-RFC1918 address ${CIDR_IP} in ${DIRECTION} rule." "${REGION}"
                fi
            fi
        done
    }

    for regx in ${REGIONS}; do
        SECURITY_GROUP_IDS=$(${AWSCLI} ec2 describe-security-groups --region ${regx} --query 'SecurityGroups[*].GroupId' --output text | xargs)
        for SECURITY_GROUP in ${SECURITY_GROUP_IDS}; do
            check_cidr "${SECURITY_GROUP}" "inbound" "${regx}"
            check_cidr "${SECURITY_GROUP}" "outbound" "${regx}"
        done
    done
}